Art of refrigeration



Feb. 6, 1951 sc u z ETAL 2,540,550

ART OF REFRIGERATION Filed Feb. 2, 1946 2 Sheets-Sheet l FlG.l

1951 v E. L. SCHULZ EI'AL 2,540,550

ART OF REFRIGERATION Filed Feb. 2, 1946 2 Sheets-Sheet 2 FIG.3

FIG. 7 INIV'ENTOR. FIG. 8 L4 By 5 4,; '5 -4 Patented Feb. 6, 1951 ART or REFRIGERATION Edward L. Schulz, Lakewood, Ohio, and Edward A. Bailey, Marietta, N. Y., assignors to Carrier Corporation, Syracuse, N. Y., a corporation of Delaware Application February 2, 1946, Serial No. 645,184

9 Claims.

This invention relates to the art of refrigeration and more particularly to control arrangements for regulating the production of refrigeration effect, the control arrangements being responsive to variations in load conditions and being adapted to compensate for overload conditions arising from unforseen causes. The control arrangements may also be responsive to the temperature of the area being served if desired to compensate for conditions of underload.

The general object of the invention is to provide simple and efiective control arrangements for regulating the action of an expansion valve to compensate automatically for conditions re,- sulting in undersirable condenser pressures or suction pressures.

A feature of the invention resides in the provision of a metering arrangement in the high side of a refrigeration system for reducing the rate of admission of refrigerant to an evaporator or cooler when the condenser pressure exceeds a predetermined maximum.

Another feature of the invention is the provision of control means in an equalizer line connecting an expansion valve and the suction line which is adapted to close to permit an increase in pressure in the equalizer line thereby urging the expansion valve toward a closed position and decreasing the flow of refrigerant to the evaporator or cooler.

Another feature of the invention resides in the provision of a metering arrangement in the high side of a refrigeration system for increasing or decreasing the rate of admission of refrigerant to an evaporator or cooler when the temperature of the area being conditioned varies from a predetermined level.

In the operation of refrigeration systems, it is usual to employ an expansion valve for maintaining a desired predetermined super-heat at the exit or discharge end of the evaporator; the valve is usually set to provide a super-heat of 12 to 15 as may be desired.

The expansion valve tries to maintain this degree of super-heat in the suction line regardless of any undesirable situation such as excessive head pressure which may develop in the rest of the system. This is true particularly of liquid charged expansion valves. However, gas charged expansion valves do limit excessive head pressure to a certain extent since they remain closed until the suction pressure drops below a certain predetermined point depending on the chargev of the thermal bulb. These types of expansion valves do not protect the rest of the system sure switch which stops the refrigeration mareceiver I.

chine. This gives protection but at the same time cuts off all refrigeration and hence the use of such device per se is undesirable and unsatisfactory.

This invention is designed to obviate such undesirable results by reducing the amount of refrigerant admitted to the evaporator to that which can safely be handled by the compressor. As a result, regardless of deficiencies in operation of the condenser, or regardless of load conditions affecting the system, the control arrangement will enable the system to function effectively with maximum utility having due regard for such impairment as may affect the operation of any of the component parts.

The control arrangements of the present invention are directed to simple and inexpensive means of modulating the action of an expansion valve or supplementing the operation of an expansion valve to limit the quantity of refrigerant flowing through the system to that which can be handled safely by the compressor without overload.

The attached drawings illustrate a preferred embodiment of our invention in which:

Figure 1 is a diagrammatic view of a refrigeration system illustrating a preferred form of the present invention;

Figure 2 is a diagrammatic view of a, control valve for use in the system shown in Figure 1';

Figure 3 is a diagrammatic view of a refrigeration system illustrating a modified form of the invention;

Figure 4 is a diagrammatic view of a control valve for use in the system shown in Figure 3:

and

Figures 5, 6, 7 and 8 illustrate modified forms of the invention.

Referring to the drawings there is shown a compressor of the reciprocating type, although it may be of any desired type, adapted to discharge compressed refrigerant gas through line 3 to a condenser 4. Condenser 4 may be air or water cooled as desired. As illustrated, condenser 4 is air cooled by means of fan 5. Condensed refrigerant enters line 6 and flows to Refrigerant from the receiver 1 proceeds through discharge line 8, expansion valve and evaporator III, returning to compressor 2 through line II. Expansion valve 9 operates in the usual manner under control of bulb I2 attached to the discharge side of evaporator III to maintain a predetermined super-heat in therefrlgerant discharged from evaporator II. An equalizer line I3 is provided connecting expansion valve 9 and suction line II. Equalizer line I3, as is well known in the art, serves to equalize pressure imposed upon the diaphragm of expansion valve 8.

A line I4 is provided connecting discharge line 8 and equalizer line I3. An orifice I5 is disposed in line I4 and serves to permit a minor amount of refrigerant to bleed through line I4 into equalizer line I3.

A valve I6 is disposed in equalizer line I3; valve II is disposed in equalizer line I3 between the juncture of line I I with line I3 and the juncture of line IS with line II. A line I1 connects discharge line 8 with valve I6. Under normal conditions valve I8 remains in an open position in order not to interfere with the minor amount of liquid refrigerant flowing through equalizer line I3 and being discharged into suction line II. In other words, when the system operates normally the pressure in line 8 (the condensing pressure) remains below a predetermined upper limit, of say 200 pounds. Under such conditions, valve I6 remains open and the system operates as though valve I6 was omitted therefrom.

Assuming that the system becomes overloaded due, for example, to the break-down of fan 5 used for cooling the condenser (or due to the breakdown of the water supply if the condenser depends upon water for refrigerant cooling purposes), then the pressure in condenser 4, receiver I and line 8 rises. If the failure to provide condenser cooling becomes so serious as to cause the pressure to rise above the predetermined level of 200 pounds in the example given, then damage to the system would result unless operation was stopped or the capacity of the system effectively reduced so that only that amount of refrigerant is handled which could be condensed effectively.

When pressure in discharge line 8 (condensing pressure) exceeds a predetermined maximum of 200 pounds, control valve I6 will operat responsive to a rise in pressure above the set figure to decrease progressively the amount of refrigerant permitted to flow through equalizer line I3. Since a minor amount of refrigerant is permitted to bleed through line I4 to equalizer line I3. the pressure under the diaphragm of expansion valve 9 is increased urging valve 9 toward a closed posltion and decreasing progressively the amount of refrigerant permitted to enter evaporator III through expansion valve 9. The volume of refrigerant'admitted to evaporator ID will decrease as the condensing pressure increases above the predetermined maximum pressure of 200 pounds. If the fault in the system causing the increase in condensing pressure is due to impaired condensing action, but assuming some condensing action does take place, then valve 9 will permit a quantity of refrigerant to be admitted to evaporator III, such reduced volume being the maximum which the system can handle without a further increase in condensing pressure.

Assuming that a pressure, of say 200 pounds, which is below the danger point would not be exceeded if only a portion of the normal volume of refrigerant is permitted to be circulated in the system, then control valve I6 will constrict the flow of refri erant in equalizer line I 3, increasing the pressure in line I3 between valve I 6 and valve 9 and permitting the increased pressure to be exerted upon the diaphragm of expansion valve 9 to urge the valve toward a closed position. Valve 9 thus constrict the flow of refrigerant from line 8 to evaporator I0 so that only such percentage of the normal amount of refrigerant will be delivered by the system.

Since operation at reduced efiiciency is undesirable, suitable means may be provided if desired for informing the operator of abnormal conditions. Under conditions of serious impairment, such as when fan 5 breaks down or when the supply of cooling fluid to a water cooled condenser is completely shut off, the system will be unable to function effectively even with a much reduced supply of refrigerant. If desired, a suitable control may be provided to stop the operation of compressor 2.

For purposes of illustration, control valve Ii may take the form shown in Figure 2. Control valve I6 includes a housing I8 having diaphragm I9 disposed in a chamber 20 therein. The diaphragm I9 is flexed in one direction by a spring 2I. Diaphragm I9 is attached to a valve stem 22 carrying a valve member 23 adapted to close port 24 in housing I8. Under normal operation, spring 2| flexes diaphragm I9 in one direction to move valve member 23 away from port 24 thus opening port 24 through the housing.

Chamber 20 on the opposite side of diaphragm I9 is connected to line I! and through line I! is exposed to condenser pressure. An increase in condenser pressure above a predetermined level flexes diaphragm I 9 in the opposite direction and urges stem 22 toward port 24 thus partially or completely closing valve I6 in accordance with the increase in condenser pressure above the predetermined level.

In many cases it is desirable to control the flow of refrigerant to evaporator III in accordance with variations in load in an area served by the system. In such case (refer to Figure 5) valve I6 may be provided with a suitable diaphragm 25 and bulb 26. Bulb 26 preferably is disposed in the area served by the refrigeration system. A decrease in the temperature of the area being served, reflected by bulb 26, serves to move valve member 23 to a position partially or completely closing port 24 and permitting an increase in pressure in line I3 to move valve 9 toward a closed position.

In some cases it may be desired to provide a second control valve 21 (refer to Figure 6) responsive to the temperature of the area being served as reflected by bulb 28. Valve 21 may be disposed in equalizer line I3. Upon a decrease in temperature in the area being served, as reflected by bulb 28, valve 21 is urged toward closed position thus partially or completely preventing the flow of refrigerant through line I3 and permitting refrigerant flowing from line 8 through line It to line I3 to increase the pressure in line I3 thus urging expansion valve 9 toward a closed position and decreasing the amount of refrigerant passing toevaporator I0.

Figure 3 illustrates a modified form of the invention. Orifice I 5 is disposed in equalizer line I3. A control valve 29 is disposed in a line 30 connecting discharge line 8 and equalizer line I3 as shown. Control valve 29 under normal operation is maintained in a closed position. If, due to failure of the condenser, for example, pressure in line 8 increases above a predetermined maximum, valve 29 is urged toward an open position permitting refrigerant to flow freely into equalizer line i3. Orifice IS in line l3 restricts the free flow of refrigerant in line i3 and consequently permits pressure to build up therein between orifice i5 and valve 9. The increased pressure in line I3 is exerted upon the diaphragm of expansion valve 9 and serves to urge valve 9 toward a closed position thus decreasing the amount of refrigerant passing to evaporator ID.

A simple control valve for this purpose is illustrated in Figure 4. Such structure includes a housing 3i containing diaphragm 32. Diaphragm 32' carries a valve stem 33 terminating in a valve member 34 adapted to close port 35 in the valve. A spring 36 flexes diaphragm 32 in one direction. Pressure of refrigerant in line 30 is exerted upon the opposite side of diaphragm 32 and opposed to the pressure exerted thereon by spring 36. An increase in pressure above a predetermined level flexes diaphragm 32 in an opposite direction,

raising valve member 34 and permitting the passage of refrigerant through port 35.

The system illustrated in Figure 3 is substantially similar to the system illustrated in Figure 1 except that a modified form of control valve is provided and that the position of orifice IS in the system is changed. If desired, the system shown in Figure 3 may be modified as shown in Fig. 7 in order that control valve 29 may be responsive to a change in the temperature of the area being served to compensate for conditions of partial load. If desired, a special control valve may be provided for this purpose as shown in Figure 8. In such case a line 31 may be provided connecting discharge line 8 and equalizer line [3. A control valve 38 is disposed in line 31. Control valve 38 under normal conditions is maintained in a closed or partially closed position, preventing substantial passage of refrigerant from discharge line 8 to equalizer line l3. A decrease in temperature in the area being conditioned, reflected by bulb 39 disposed in such area. serves to move valve 38 toward an open position permitting passage of refrigerant from line 8 to line l3. Orifice l5 in line l3 restricts the passage of refrigerant causing pressure to increase in equalizer line l3, which actuates valve 9 to move toward a closed position decreasing the amount of refrigerant passing to evaporator Hi.

The present invention provides a ready and simple control arrangement for a refrigeration system to regulate the refrigeration efiect in response to variations in load conditions. The system compensates for overload conditions arising from unforeseen causes. The control means so provided compensate automatically for conditions resulting in undesirable condenser pressure which imposes an overload on the system and compensates for conditions resulting in partial load imposed upon the system.

While we have described and illustrated a preferred embodiment of our invention, it will be understood our invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. In a refrigeration system, the combination of a compressor, a condenser, an expansion valve and an evaporator disposed in a closed circuit, means for controlling the operation of the expansion valve, an equalizer line connecting the expansion valve and the suction line, a line connecting the discharge line and the equalizer line, and control means responsive to an increase in pressure in the discharge line above a predetermined level for urging the expansion valve toward a closed position to decrease the quantit of refrigerant passing to the evaporator.

2. In a refrigeration system, the combination of a compressor, a condenser connected to the compressor, an expansion valve, means for controlling the operation of the expansion valve, a discharge line connecting the expansion valve to the condenser, an evaporator connected to said expansion valve, a suction line connecting the evaporator to the compressor, an equalizer line connecting the expansion valve with the suction line', a control valve in the equalizer line responsive to an increase in pressure in the discharge line above a predetermined level to move toward a closed position, a line connecting the discharge line and the equalizer line, an orifice in the connecting line, and a line connecting the control valve with the discharge line, to permit an increase in pressure above'a predetermined level in the discharge line to actuate the control valve to move toward a closed position thereby increasing the pressure in the portion of the equalizer line connecting the control valve and the expansion valve to urge the expansion valve toward a closed position.

3. In a refrigeration system, the combination of a compressor, a condenser, an expansion valve and an evaporator disposed in a closed circuit, an equalizer line connecting the expansion valve and the suction line, a line connecting the discharge line to the equalizer line, and means in the equalizer line responsive to the temperature of an area being served adapted to close the equalizer line in response to a decrease in temperature below a predetermined level thereby permitting pressure to increase in the portion of the equalizer line between said means and the expansion valve to urge the expansion valve toward a closed position.

4. In a refrigeration system, the combination of a compressor, a condenser connected to the compressor, an expansion valve, a discharge line connecting the condenser with the expansion valve, an evaporator connected to the expansion valve, a suction line connecting the evaporator and the compressor, an equalizer line connecting the expansion valve with the suction line, a line connecting the discharge line and the equalizer line, an orifice in said line, a control valve in the equalizer line connected to the discharge line, an increase in condenser pressure above a predetermined level actuating the control valve to move toward a closed position thereby increasing the pressure in the portion of the equalizer line connecting the control valve and the expansion valve to urge the expansion valve toward a closed position, and means responsive to a decrease in temperature in an area being served adapted to move the control valve toward a closed position.

5. In a refrigeration system, the combination of a compressor, a condenser connected to the compressor, an expansion valve, a discharge line connecting the condenser with the expansion valve, an evaporator connected to the expansion valve, a suction line connecting the evaporator and the compressor, an equalizer line connecting the suction line and the expansion valve, a line connecting the discharge line and the equalizer line, an orifice in said line, a control valve in the equalizer line, a line connecting the control valve to the discharge line, a second control valve in the equalizer line, and means for actuating said second control valve in response to a decrease in temperature in an area being served,

said first control valve being operable in response to an increase in condenser pressure above a predetermined level to move toward a closed position thereby permitting pressure to increase in the portion 01. the equalizer line connecting the first control valve and the expansion valve to urge the expansion valve toward a closed position.

6. In a refrigerating system, the combination of a compressor, acondenser connected to the compressor, an expansion valve, a discharge line connecting the expansion valve and the condenser, an evaporator connected to the expansion valve, a suction line connecting the evaporator to the compressor, an equalizer line connecting the suction line and the expansion valve, an orifice in said equalizer line, a line connecting the discharge line and the equalizer line, and a control valve disposed in said connecting line, said control valve in response to an increase in condenser pressure above a predetermined level moving toward an open position to permit an increase in pressure in the equalizer line thereby urging the expansion valve toward a closed position.

7. A refrigeration system according to claim 6 in which means are provided for actuating the control valve in response to a decrease in room temperature to move toward an open position.

8. In a refrigerating system, the combination of a compressor, a condenser connected to said compressor, an expansion valve, a discharge line connecting the expansion valve and the condenser, an evaporator connected to said expansion valve, a suction line connecting the evaporator to the compressor, an equalizer line connecting the suction line and the expansion valve, a line connecting the discharge line and the equalizer line, a control valve in said line, and means for actuating said control valve in response to a decrease in temperature in an area being served, actuation of said control valve tending to move the valve toward an open position to permit an increase in pressure in the equalizer line thereby urging the expansion valve toward a closed position.

9. In a refrigerating system, the combination of a compressor, a condenser connected to the compressor, an expansion valve, a discharge line connecting the expansion valve and the condenser, an evaporator connected to the expansion valve, a suction line connecting the evaporator to the compressor, an equalizer line connecting the expansion valve to the suction line, an orifice in the equalizer line, a line connecting the discharge line and the equalizer line, a control valve in said line responsive to an increase in condenser pressure above a predetermined level to move toward an open position permitting an increase in pressure in the equalizer line to urge the expansion valve toward a closed position, a second line connecting the discharge line and the equalizer line, a second control valve in said second line, and means responsive to a decrease in temperature in an area being served to actuate said second control valve, a decrease in temperature in an area being served actuating said second control valve to move toward an open position thereby permitting an increase in pressure in the equalizer line to urge the expansion valve toward a closed position.

EDWARD L. SCHULZ. EDWARD A. BAILEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

